Testing in Ruby - Speaker Deck

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Testing in Ruby

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I’m Darcy

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Fellow student here

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I make APIs for iOS Apps in Ruby

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Q: What is testing?

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Automated Testing

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Veriﬁable contracts

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Given this, I expect that.

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“Test Suites”

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Q: Why test?

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Testing as a contract

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Prevent regressions.

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Verify your assumptions

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Conﬁrm you’re understanding

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Things you forget.

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Real World Example: Merging data.

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Testing as a design tool

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“T.D.D.”

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Test-ﬁrst development

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Red Green Refactor

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Write a failing test

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require 'test_helper' class PersonTest < ActiveSupport::TestCase test "making a full name" do person = Person.new first_name: "Bob", last_name: "Smith" assert_equal "Bob Smith", person.full_name end end

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# Running tests: E Finished tests in 0.057601s, 17.3608 tests/s, 0.0000 assertions/s. 1) Error: PersonTest#test_making_a_full_name: NoMethodError: undefined method `full_name' for # test/models/person_test.rb:7:in `block in ' 1 tests, 0 assertions, 0 failures, 1 errors, 0 skips ==============================================================================

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Make it pass

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class Person < ActiveRecord::Base def full_name first_name + " " + last_name end end

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# Running tests: . Finished tests in 0.132392s, 7.5533 tests/s, 7.5533 assertions/s. 1 tests, 1 assertions, 0 failures, 0 errors, 0 skips ==============================================================================

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Refactor it.

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class Person < ActiveRecord::Base def full_name "#{first_name} #{last_name}".strip end end

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# Running tests: . Finished tests in 0.177100s, 5.6465 tests/s, 5.6465 assertions/s. 1 tests, 1 assertions, 0 failures, 0 errors, 0 skips ==============================================================================

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We’re all human.

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Work out what you want

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Write as little as possible to make it happen

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Work out what you don’t know

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Testing as documentation

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Testing in Rails

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Rails <3’s testing

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Testing is a standard part of Rails

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$ rake

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Run options: --seed 13019 # Running tests: ...FE Finished tests in 0.077580s, 64.4496 tests/s, 51.5597 assertions/s. 1) Failure: PersonTest#test_making_a_name_with_no_given_names [/Users/sutto/Code/test_project/test/models/person_test.rb:22]: Expected: nil Actual: "" 2) Error: PersonTest#test_making_searching_for_users: NoMethodError: undeﬁned method `search' for # test/models/person_test.rb:28:in `block in ' 5 tests, 4 assertions, 1 failures, 1 errors, 0 skips ============================================================================== Run options: --seed 5103 # Running tests: . Finished tests in 0.086914s, 11.5056 tests/s, 11.5056 assertions/s. 1 tests, 1 assertions, 0 failures, 0 errors, 0 skips ==============================================================================

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Generates automatically generate stubs for you.

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xUnit

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JUnit

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Test::Unit

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MiniTest

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Assertions

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assert

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assert_equal 2, (1 + 1)

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Unit / Model Tests

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Small, independent bits of functionality.

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Minimal set of dependencies

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test "making a name with first and last name" do person = Person.new first_name: "Bob", last_name: "Smith" assert_equal "Bob Smith", person.full_name end test "making a name with first name only" do person = Person.new first_name: "Bob" assert_equal "Bob", person.full_name end test "making a name with last name only" do person = Person.new last_name: "Smith" assert_equal "Smith", person.full_name end test "making a name with no given names" do person = Person.new assert_equal nil, person.full_name end

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Test edge cases

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Small, fast and easy to test assumptions.

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test "making searching for users" do person = Person.create! first_name: "Bob", last_name: "Smith" # Actually hit the database and get a result... Person.search('Bob Smith').should == [person] end

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Functional / Controller Tests

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Test how the model, view and controller interact

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require 'test_helper' class PeopleControllerTest < ActionController::TestCase test "should list users" do person = Person.create! get :index assert_equal [person], assigns(:people) end end

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test "redirecting when not logged in" do get :index assert_response :redirect assert_redirected_to some_other_page end test "visible when logged in" do get :index assert_response :success end

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Guarantees*.

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* Only test what you specify, nothing more.

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Checks the glue.

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Integration tests.

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The bigger picture

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E.g. user stories

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User logs in, purchases an item, order is placed.

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Slower to run, but test everything together.

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Taking it Further

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Full Stack Tests

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Coverage Tools

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Simplecov

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See code that isn’t tested

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BDD

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RSpec

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minitest-spec

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What I’ve learnt about testing

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Over testing is bad.

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Slow tests sucks.

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Testing should be instinctive

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Don’t get stuck on numbers (coverage, number of tests)

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Good tests inspire conﬁdence

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Only test what you implement

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If you have to be told to test, it’s probably not going to help

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It takes time to learn to write good tests

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Don’t be afraid to write tests before code

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Most importantly, writing tests costs less long term.